Thin printed circuit board

ABSTRACT

The present invention is directed to a printed circuit board, comprising: at least one chip; and a board comprising at least one aperture corresponding to each chip, for enabling each chip to be placed inside the corresponding aperture, thereby enabling reducing the thickness of the printed circuit board to that of the thickest chip. According to one embodiment of the invention, the chip is placed on the board with the upper side of the chip up. According to another embodiment of the invention, the chip is placed on the board with the upper side of the chip down. According to one embodiment of the invention the legs of the chip have “straight” form. According to another embodiment of the invention the legs of the chip have “bent” form.

FIELD OF THE INVENTION

The present invention relates to the field of mounting chips on printedcircuit boards.

BACKGROUND OF THE INVENTION

The term Integrated Circuit (IC) refers in the art as to amicroelectronic semiconductor device consisting of many interconnectedtransistors and other electronic components. ICs are constructed on asmall rectangle cut from a Silicon (or for special applications,Sapphire) wafer. Integrated circuits are also known as “Chips”.

The term Printed Circuit Board (PCB) refers in the art as to a printedboard on which chips and other electronic components are placed.

The term Chip Mount Technology refers in the art as to a technology ofelectronic assembly manufacturing, such as TOB, COB or Flip chip, whichconnects bare integrated circuit to a printed board (substrate). Thereare several types of flip chip mounting methods, each one focused in adifferent aspect, such as low cost performance, high bondingtemperature, bonding reliability, process flexibility, etc.

As the currently popular products, such as cellular telephones, PDAs,and laptop computers, get smaller, decreasing the thickness of a PCBbecomes an essential issue. Nevertheless the methods of the prior arthave not provided a satisfactory solution for decreasing the thicknessof a PCB.

It is an object of the present invention to provide a PCB whosethickness is less than a prior art PCB which comprises the same chips.

It is another object of the present invention to provide technologiesfor manufacturing a PCB, whose thickness is less than a prior art PCBwhich comprises the same chips.

Other objects and advantages of the invention will become apparent asthe description proceeds.

SUMMARY OF THE INVENTION

The present invention is directed to a printed circuit board,comprising: at least one chip; and a board comprising at least oneaperture corresponding to each chip, for enabling each chip to be placedinside the corresponding aperture, thereby enabling reducing thethickness of the printed circuit board to that of the thickest chip.According to one embodiment of the invention, the chip is placed on theboard with the upper side of the chip up. According to anotherembodiment of the invention, the chip is placed on the board with theupper side of the chip down. According to one embodiment of theinvention the legs of the chip have “straight” form. According toanother embodiment of the invention the legs of the chip have “bent”form.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention may be better understood in conjunction with thefollowing figures:

FIG. 1 illustrates a PCB, according to a preferred embodiment of theinvention.

FIG. 2 is a “sliced” cross section of the board illustrated in FIG. 1.

FIG. 3 illustrates a cross section along the mounting region of chips 20and 50 of FIG. 1.

FIG. 4 illustrates the PCB of FIG. 1, in an upside-down position.

FIG. 5 illustrates a cross section along the mounting region of chips 20and 50 of FIG. 1 in a three-dimensional view.

FIG. 6 illustrates a chip having a “straight” form legs mounted on aboard, according to the invention.

FIG. 7 illustrates a “bent” form legs mounted on a board, according tothe invention.

FIG. 8 illustrates a “bent” form legs mounted on a board, according toanother embodiment of the invention.

DETAILED DESCRIPTION OF PREFERED EMBODIMENTS

FIG. 1 illustrates a PCB, according to a preferred embodiment of theinvention. Chips 10, 20, 30, 40, 50 and 60 are mounted on board 100.

In order to facilitate the text to follow, it should be noted that thewidth corresponds to the X axis, the length corresponds to the Y axis,and the thickness corresponds to the Z axis of the board. Thus, thethickness of a PCB is actually the thickest point of the PCB (i.e. alongthe Z axis).

FIG. 2 is a “sliced” cross section of the board illustrated in FIG. 1.Apertures 11, 21, 31, and 41 correspond to the chips 10, 20, 30 and 40.Thus, when one of the chips 10 to 40 is mounted on the board 100, thecorresponding aperture enables to mount the chip such that the size ofthe outstanding part of a chip is diminished by the thickness of theboard 100.

FIGS. 3 and 4 illustrate a cross section along the mounting regions ofchips 20 and 50. Chip 50 is mounted according to the prior art, whilechip 20 is mounted according to the present invention, i.e. into theaperture 21. The thickness 102, which is reflected from the fact thatthe chip 20 is inserted into the aperture 21, is less than the thickness102.

The width and length of each aperture 11 to 41 is greater than thecorresponding width and length of its corresponding chip, therebyallowing placing the chip inside the aperture. However, at least thewidth or the length of an aperture is smaller than the width or lengthof the corresponding chip including the chip's legs, thereby allowingthe legs of the chips to contact the board 100.

FIG. 6 illustrates a chip having a “straight” form legs mounted on aboard, according to the invention. In FIG. 6 the legs 42 of chip 40 areparallel to the board 100.

FIG. 7 illustrates a “bent” form legs mounted on a board, according tothe invention. The “bent” form of the legs is common in the chipindustry.

FIG. 8 illustrates a “bent” form legs mounted on a board, according toanother embodiment of the invention. The chip 20 is mounted in anupside-down position.

It should be noted that the legs of a chip may be manufactured to beflexible, thereby allowing mounting a chip on a board while pushing thechip towards the board, thereby bending its legs to the desired form.

Those skilled in the art will appreciate that the invention can beembodied in other forms and ways, without losing the scope of theinvention. The embodiments described herein should be considered asillustrative and not restrictive.

1. A printed circuit board, comprising: at least one chip; a boardcomprising at least one aperture corresponding to said at least onechip, for enabling each said at least one chip to be placed inside saidcorresponding aperture thereof, thereby enabling reducing the thicknessof said printed circuit board to the thickest of said at least one chip.2. A printed circuit board according to claim 1, wherein said chip isplaced on said board with the upper side of said chip up.
 3. A printedcircuit board according to claim 1, wherein said chip is placed on saidbard with the upper side of said chip down.
 4. A printed circuit boardaccording to claim 1, wherein the legs of said chip have “straight”form.
 5. A printed circuit board according to claim 1, wherein the legsof said chip have “bent” form.